The dispensing of aliquots of a body liquid such as blood serum onto a dried, slide like test element is a key first step in the analysis of the liquid in an analyzer. Because of the peculiar properties of many body liquids, and the need for accurate and reproducible dispensing of a predetermined aliquot, great care has been taken in prior art devices to ensure that (a) the proper tip is used by the dispensing apparatus to direct the flow properly, and/or (b) the dispensing tip is properly presented and positioned at the test element at the time of dispensing. Examples of the technology that achieve feature (a) include tips of the type described in U.S. Pat. No. 4,347,875. Examples of the technology used to achieve features (b) include dispensing means in analyzers of the type described in U.S. Pat. Nos. 4,340,390; 4,452,899 and 4,615,360. In the latter three, the analyzer is constructed, for example, to carefully prepare the dispensing tip Just prior to the dispensing, for example, in its spacing from the test element and/or by blowing off any exterior liquid hanging on the outside of the tip.
Such care as expressed by such technologies has worked well. However, they all require expensive, peculiar apparatus that is costly either in its construction or its use. Although this is not particularly disadvantageous when constructing an expensive, high-volume analyzer, it is a drawback when constructing an inexpensive, low-volume analyzer, such as might be needed or used in remote field locations.
Therefore, prior to this invention, there has been the need to provide an inexpensive interface that will allow a conventional pipette to dispense liquid that still flows onto the test element in a predictable, accurate manner.